The present invention relates to a paging receiver and, particularly, to a paging receiver suitable for an emergency call.
The paging receiver has several kinds of functions, one of which is to change calling formats by the bearer himself according to the bearer's environmental noise or situation. However, the receiver encounters the problem that when the bearer sets calling forms such that a ringing sound volume, for example, is small, he may not be aware of a calling even if it is an emergency call.
To deal with the problem, a conventional paging receiver uses a second call number for an emergency call, which is different from a normal call number. When the paging receiver receives the second call number, it sets calling format such that a bearer can be easily aware of the emergency call immediately by generating, for example, a louder ringing sound regardless of the calling format set in the receiver. Such paging is known as "dual call service" and an example of such paging is disclosed in U.S. Pat. No. 4,438,433.
In such a conventional paging receiver, however, the second call number must be kept, leading to an increase of call numbers. Further, it is necessary to selectively use either of two call numbers, the usual call number and the emergency call number, properly in a calling side. This is troublesome.
An object of the present invention is to provide a paging receiver which, when an identical message signal is received twice within a predetermined period of time, deemes it an emergency call.